This invention relates generally to palliative treatment of bone, bone tumors and lesions, and diseases of the bone.
A variety of diseases can affect bone tissue resulting in lesions and tumors of the bone. Primary bone tumors, either benign or malignant, may originate in cartilage cells, osteoblastic (osteoid- or bone-forming) cells, fibroblastic cells, primitive mesenchymal cells, and hematopoietic cells, as well as nerve and vascular tissue, notocordal remnants, and other sites. Benign tumors of the bone include enchondroma, osteochondroma, osteoid osteoma and osteoblastoma, giant cell tumor (also malignant), chondroblastoma. Malignant tumors include multiple myeloma, metastatic carcinoma central chondrosarcoma, osteogenic sarcoma, osteogenic sarcoma medullary fibrosarcoma peripheral chondrosarcoma and Ewing""s sarcoma.
The most common forms of malignant bone tumor are attributable to metastatic disease. In fact, bone is the third most common site of metastatic disease. Treatments for bone metastases are limited in nature and generally only palliative.
Pain is one of the more prevalent and debilitating complications of bone tumors and lesions. Approximately 40% of patients with cancer develop metastatic disease; of these patients, 50% have poorly controlled pain. Unfortunately, achieving adequate pain control is often difficult and as a result, quality of life for these patients is poor. Various therapies may be employed in an attempt to provide palliative pain relief including chemotherapy, hormonal therapy, localized radiation, systemic radioisotope therapy, and surgery. Unfortunately, some patients fail to derive satisfactory pain relief with these therapies and relief, when achieved, may not occur until four to twelve weeks after the initiation of the treatment.
Pain management in terminally ill patients with metastases involving bone can be challenging. The conventional therapies may not be viable options for numerous reasons. For example, the limited efficacy or toxic side-effects of chemotherapeutic agents is problematic. Furthermore, localized radiation may not be possible due to radiation resistance of the neoplasms or limitations of further radiation of normal structures. Moreover, the patient may be either a poor surgical candidate or the patient may refuse surgery. When these methods are not possible, or are not effective, analgesic medications remain as the only current alternative therapy for pain relief. Despite these measures, the quality of life for these patients is often poor because of intolerable pain.
There is thus a need for a treatment method effective to palliate pain in patients suffering from bone-tumor associated pain.
The invention includes, in one aspect, a system for palliatively treating a pain-causing tumor on or in a bone. The system includes an instrument having a distal-end structure adapted to be inserted into the bone tumor, and activatable to ablate tumor tissue, and connecting structure for connecting the distal-end structure to an activating device. One preferred embodiment employs an electrode as the distal-end structure and connecting structure for connecting the electrode to a source of RF current.
In one general embodiment, the instrument is composed of a probe or introducer with a distal end, and at least one electrode movable from a retracted position within the probe to a deployed position extending from the probe""s distal end, forming the distal-end structure when deployed. The instrument may contain a plurality of curved, deployable electrodes, which, when deployed, create an array of deployed electrodes that defines a substantially two-dimensional surface expanse or a three-dimensional volume within the tumor. For example, for use in treating a bone tumor on the exterior or interior surface of a compact region of a bone, the electrodes, when deployed, may form an array that defines a two-dimensional expanse that is coextensive with a portion of the surface of the compact bone region surrounded by the tumor. As other examples, the deployed electrodes may form a three-dimensional volume that encompasses the instrument""s distal tip, or three-dimensional volume that converges at the distal tip. The curvature of one or more of the electrodes may be shapable, prior to use, such that the electrode(s), when inserted into the tumor, define a selected geometry within the tumor.
In one general embodiment, at least one of the electrodes is a needle forming a conduit through which liquid can be injected into the tumor, either prior to, during, or following tumor ablation. This embodiment includes additional connecting structure for connecting the needle to a source of liquid under pressure.
In another aspect, the invention includes a method of palliatively treating a pain-causing bone tumor of the type indicated above. The method includes the steps of locating the position of the bone tumor, positioning against or adjacent the located bone tumor, the distal end of an instrument having a distal-end structure which can be activated to ablate tissue, and with the structure inserted into or against the bone tumor, activating the structure under conditions effective to ablate at least a portion of the tumor. One preferred embodiment employs an electrode as the distal-end structure and connecting structure for connecting the electrode to a source of RF current. The instrument used in the method may have single or plural deployable electrodes, with various geometries in the deployed state, as discussed above.
In one general embodiment, which preferably employs a distal-end electrode and an RF or other heat-producing activating source, the method further includes injecting a liquid into the tumor, either prior to, during, or following tumor ablation. For example, prior to or during RF ablation, an electrolyte solution may be injected into the tumor, to enhance the conductivity of the tumor during the applying of RF current to the electrode(s). Alternatively, or in addition, the injected liquid may be a polymer liquid injected into the tumor or tumor region before, during, or following the activating (heating) step, depending on temperature conditions needed to promote hardening of the polymer once injected into the tumor site.
In still another aspect, the invention includes a method of injecting into an internal body site in a subject, a polymer liquid designed to harden at the body site. The polymer hardening may be due to heat-induced or promoted polymerization, e.g., cross-linking at the site, or the hardening of a thermoplastic polymer below its glass transition temperature. The method includes first positioning against or adjacent the internal body site, the distal end of an instrument having a distal-end electrode needle which can be activated to produce localized heating. With the tip so positioned, liquid polymer is injected through an electrode needle, either before, during, or following activation of the needle, such that the needle and surrounding tumor region is at a temperature that allows introduction of the polymer solution through the needle and hardening at the site of injection. In a preferred embodiment, the polymer liquid is polymethylmethacrylate, and the activating step is effective to maintain the temperature of the polymer liquid above its glass transition temperature while the liquid is being injected into the tumor.
In still another aspect, the invention includes a method of injecting a polymer liquid into an internal body site in a subject to form a solidified or hardened polymer plug at the site. The method includes positioning against or adjacent the internal body site, the distal end of an instrument having a distal-end electrode needle which can be activated to produce localized heating. With the needle so positioned, it is activated under heating conditions. The polymer liquid is then injected into the tumor, before, during or following the activating step, such that the needle and surrounding tumor region is at a temperature that allows introduction of the polymer solution through the needle and hardening at the site of injection.
For use in palliatively treating a pain-causing bone tumor, the needle is positioned within the tumor, the activating step is effective to ablate tumor tissue by heating, and the polymer liquid, when it hardens at the injection site, is effective to stabilize movement the ablated tumor region. In one preferred embodiment, the polymer liquid is a polymethylmethacrylate. The injecting step may include injecting the liquid through an electrode needle, and the activating step is effective to maintain the temperature of the polymer liquid above its glass transition temperature while the liquid is being injected through the needle.
These and other objects and features of the invention will become more fully apparent when the following detailed description of the invention is read in conjunction with the accompanying figures.